Aminocarbazole-sulphonic acid



Patented Oct. 4, 1932 UNlE EDUAEID 'ISCHUNKUR AND ERNST KRACHT, OF OOLOGNE-MULHEIRI, AND ERNST HERDIEGKERHQFF, OF OPLADEN, GERMANY, ASSIGNORS 'IO GENERAL ANILINE WORKS, INC., OF NEW YQEK, N. Y., A CORPORATION OF DELAWARE AMINOCARBAZOLE-SULPHONIC ACID 7 No Drawing. Application filed July 15, 1931, Serial No. 551,044, and in Germany July 18, 1930.

- phonic acid by sulphonating diphenyl is described by Latschinow in Berichte der Deutschen Ohemischen Gesellschaft, volume 6, page 194. When the process is carried out according to these directions a mixture of 'diphenyl-monoand -disulph-onic acids is,

however, obtained, which leads to a less satisfactory yield and a more impure product in the manufacture of triaminodiphenylsulphonic acid.

Now we have found that the diphenyl-4:- sulphonic acid is obtainable from diphenyl in an almost uniform condition provided that the sulphonatio-n of diphenyl by means of concentrated sulphuric acid is commenced at room temperature and thereafter the temperature is gradually raised to about 65 C. (Latschinow sulphonated diphenyl with concentrated sulphuric acid directly at water bath temperature.)

The diphenyLd-sulphonic acid obtained ac cording to the new method of working can be directly nitrated by means of mixed acid to form trinitrodiphenylAesulphonic acid in the suspension resulting from the sulphonation with the result that the new process can be carried out in the factory easily and conveniently. After the isolation of the trinitrodiphenyl-d-sulphonic acid the same can be converted in aqueous suspension into triaminodiphenyl-d-snlphonic acid by known reducing agents, such as for example, iron and hydrochloric acid. The resulting procluct is the 2.24!-triaminodiphenyl-4-sulphonic acid, which serves as intermediate product in the manufacture of 2-aminocarbazole-7-sulphonic acid.

When the 2.2 l-triaminodiphenyl-d-sul-. phonic acid is heated in the presence of aqueous mineral acid or mineral acid salts, say a 5 to 20% aqueous hydrochloric or sulphuric acid, to only about 150170 (l. for several hours, ammonia is split off with the production of hitherto unknown 2-amino-' carbaZole-7-sulphonic acid.

This reaction can be favorably influenced by the addition of zinc chloride, aluminium chloride, barium chloride or the like. By further heating of the same charge to about 180-200 C. 2-aminocarbazole is produced inv a good yield.

From the products thus rendered available a number of other carbazoles, substituted in the 2-position, can readily be produced by further reactions, for example, by replacing according to Sandmeyer the amino-group by hydroxyl, chlorine, cyanogen and the like. Furthermore the 2-aminocarbazole-7-sul-c phonic acid can be converted into the 2-amino-7-hydroxycarbazole by alkali fusion or into the 2-aminocarbazole by heating in dilute aqueous mineral acid.

The following example will further illustrate the invention, without limiting it thereto:

Example 2.2 cwid.

(a) Sulphonation.100 kgs. of diphenyl are mixed while stirring with 300 kgs. of sulphuric acid of 66 B. for one hour at room temperature after which the temperature is then slowly raised in the course of 3 hours to about 65 C. while stirring and maintained for another 1-2 hours at about 65 C. The sulphonation of the diphenyl to diphenyl-l-sulphonic'acid is then complete.

(b) Nc'tratz'0n.440 kgs. of mixed acid of about 83% of nitric acid and 67% of sul-' phuric acid are dropped into the sulphonation mass at 60 C. (at a lower temperature the mass solidifies), the temperature is then raised to about 85 C. and the mixture is stirred at this temperature for several .4 trz'amnodz'phenyl 4 sulphom'c hours longer. Thereafter the nitration mass is poured into ice-water and rendered nearly neutral to Congo red with alkali. The greater part of the trinitrodiphenyl monosulphonic acid is thereby precipitated. It is filtered with suction and washed with common salt solution. The trinitrodiphenyl monosulphonic acid remaining in the filtrate is salted out withcommon salt, filtered with suction and washed with common salt solution. i

(0) Reduction. The trinitrodiphenyl monosulphonic acid as obtained under (6) is reduced in aqueous suspension in about 58 hours at 100 C. by means of 7 50 kgs. of iron and about litres of 30% acetic acid or hydrochloric acid. while well'stirring. The magma from the reduction is rendered alkaline with sodium carbonate and filtered from the iron sludge. The filtrate is evaporated to about 1 chm. and rendered neutralto Congo red with hydrochloric acid. The 2.2'-l' triaminodiphenyl-l-sulphonic acid separates on cooling; analysis and chemical reactions confirm the constitution of the 2.2-t-triamino-diphenyl-l-sulphonic acid.

Q-aminocarbazoZe-V-sulphonic acid.-

50 lags. of pure triaminodiphenyl sulphonic acid are heated with 2500 litres of 3.5% hydrochloric acid or sulphuric acid for about 6 hours to about 160 C. The precipitated product is filtered, then dissolved in dilute caustic soda, filtered and the 2- aminocarbazole-7-sulphonic acid is precipitated with hydrochloric acid, filtered with suction and dried. It is a white powder, insoluble in water, soluble in alkalies and is a Valuable intermediate product for the manufacture of dyestuifs.

2-amin00arba20Ze.-

50 kgs. of pure triaminodiphenyl sulphonic acid are heated with 2500 litres of 2% hydrochloric acid or sulphuric acid to about 200 C. for 6 hours. The precipitated product is filtered, the 2-aminocarbazole which remains in the filtrate is salted out and also filtered. By dissolving and precipitating from dilute hydrochloric acid Q-aminocarbazole is obtained in a good yield.

We claim:

1. The process which comprises sulpho-,

nating diphenyl by starting the sulphonation at room temperature, raising the same to about 65 C. and keeping at this temperature until the sulphonation is complete, nitrating the diphenyll-sulphonic acid formed, reducing the 2.2-el-trinitrodiphenyl-t-sulphonic acid to the 2.2-4-triaminodiphenyll-sulphonic acid and heating the 22'4-triaminodiphenyll-sulphonic acid in a dilute aqueous mineral acid at a tempera- I ture between 150 and 17 0 C.

2. As a new product the 2-aminocarbazole- 7 -sulphonic acid, being a white substance, insoluble in water, soluble in alkalies and be tures.

EDUABD TSCHUNKUR. ERNST KRACHT. v ERNST HERDIEGKERHOFF. 

